Tratner I, Nahon J L, Sala-Trepat J M
Laboratoire d'Enzymologie, CNRS, Gif-sur-Yvette, France.
Nucleic Acids Res. 1988 Apr 11;16(7):2749-63. doi: 10.1093/nar/16.7.2749.
By use of different restriction enzymes sensitive to internal cytosine methylation (HpaII, AvaI, HhaI) we have analysed the methylation patterns of albumin and AFP genes in tissues and cell lines with high (liver, yolk sac, hepatoma cell lines), low (fetal and neonatal kidney) or undetectable (spleen, JF1 fibroblasts) expression of either gene. We show that expression of the AFP gene is associated to the demethylation of a whole region or domain extending from -4 to +3 Kb. Moreover, demethylation of a site located at the upstream limit of this domain appears to be correlated with the commitment of the cell type to synthesize AFP. As concerns the albumin gene, we show that the domain in which demethylation is correlated with active gene transcription in hepatoma cell lines has different borders than in tissue. This difference might be related to the different amounts of mRNA synthesized or to an alteration in gene regulation in tumor cells. Finally, we show that low expression of albumin and AFP genes in fetal and neonatal kidney is not correlated with domain demethylation, suggesting that the regulatory mechanisms of expression of these genes are different in kidney as compared with liver.
通过使用对内部胞嘧啶甲基化敏感的不同限制性内切酶（HpaII、AvaI、HhaI），我们分析了白蛋白和甲胎蛋白基因在具有高（肝脏、卵黄囊、肝癌细胞系）、低（胎儿和新生儿肾脏）或无法检测到（脾脏、JF1成纤维细胞）这两种基因表达的组织和细胞系中的甲基化模式。我们发现，甲胎蛋白基因的表达与从-4至+3 kb延伸的整个区域或结构域的去甲基化有关。此外，位于该结构域上游边界的一个位点的去甲基化似乎与细胞类型合成甲胎蛋白的倾向相关。关于白蛋白基因，我们发现，在肝癌细胞系中，去甲基化与活跃基因转录相关的结构域与在组织中的边界不同。这种差异可能与合成的mRNA量不同或肿瘤细胞中基因调控的改变有关。最后，我们发现胎儿和新生儿肾脏中白蛋白和甲胎蛋白基因的低表达与结构域去甲基化无关，这表明与肝脏相比，这些基因在肾脏中的表达调控机制不同。
